The present invention relates to tissue expanders, including tissue-expanding mammary prostheses, and to methods of making and using such tissue expanders. More particularly, the invention relates to tissue expanders capable of expanding overlying tissue into a complex shape.
Subcutaneous tissue expanders have come into wide use because of the variety of plastic surgical procedures that have been developed which either require that tissue be expanded to receive or retain an implant or that a flap of tissue be generated for use on some other part of the body.
Of the tissue expanders known in the art, some provide for expanding tissue differentially, that is, into a preselected complex shape. For example, U.S. Pat. No. 4,574,780 to Manders discloses tissue expanders which are capable of differentially expanding skin. Manders discloses that the differential expansion can be accomplished by using a tissue expander having a limited expansion portion and a differential expansion portion. The patent teaches that one way of creating a limited expansion portion is by making the expander wall of that portion thicker than the differential expansion portion. Manders also discloses that the limited expansion portion may be created by reinforcing the portion. A commercial example of a tissue expander which uses the Manders invention is SILASTIC.RTM. Differential Tissue Expander, H.P. sold by Dow Corning Wright, Arlington, Tennessee.
U.S. Pat. No. 4,651,717 to Jakubczak discloses another type tissue expander which is capable of expanding tissue into complex forms. This tissue expander consists essentially of at least two separately inflatable envelopes wherein one is used as a base and the other is smaller in volume than the first and is attached to the upper half of the base envelope to expand the tissue overlying the second envelope to a greater extend than is accomplished by the first envelope. This device requires that each envelope has an inflation means associated therewith that is separate from the other envelope's inflation means.
European Patent 196,821 discloses a tissue expander system wherein Dacron mesh may be embedded in members of the tissue expander to provide directional expansion of the tissue expander.
An implantable mammary prosthesis which can be partially inflated after the prosthesis is inserted beneath the skin is shown in product data sheet number 120318 dated 10/77 from the McGhan Medical Corporation of Santa Barbara, California, entitled "Reconstructive Mammary Implant (Birnbaum Design)" which shows a dual envelope mammary prosthesis where one part of the prosthesis has a gel-filled envelope and the other integral envelope along side the first is inflated with saline after implantation. Use of this prosthesis is described in a November, 1976, article entitled "Customized Reconstruction of the Breast After Radical and Modified Radical Mastectomies" by Birnbaum, et al. in The Western Journal of Medicine on pages 388-390. U.S. Pat. No. 4,643,733 to Becker discloses another implant which is a subcutaneous expander and a permanent reconstruction implant.
In the catheter art, U.S. Pat. No. 4,222,384 to Birtwell discloses a catheter formed from silicone rubber wherein the tip and balloon portion are molded in a single integral piece in a suitable mold but in a manner in which the tip portion of the mold is loaded with a parison of silicone rubber which will be stiff when cured and with the balloon portion of the mold being loaded with a parison of compatible silicone rubber which will be more elastic when cured.
In addition, U.S. Pat. No. 3,831,583 to Edmunds, Jr., et al. discloses an implantable device for restricting the flow of blood through a major blood vessel which includes (1) a ring, capable of inward distention, (2) a non-distensible bulb, and (3) a non-distensible tube. The patent also mentions that silicone rubber of varying degrees of hardness or cure can accommodate the need for the distensible or non-distensible portions.